The present invention relates to an improved transmission device, and more particularly, to a grease guide structure of a sunroof transmission device for opening and shutting a roof of a vehicle, such as an automobile.
In a general sunroof transmission device of this type, in consideration of safety, a worm wheel and a pinion shaft are drivingly connected through a friction clutch mechanism by fitting a retaining pawl, which projects upward from a clutch plate constituting the friction clutch mechanism arranged on the output side of the pinion shaft, in a retaining hole formed on the bottom plane of the worm wheel to which a motor driving force is input. However, if grease filled in a rotatable portion or a gear engaging portion of the worm wheel flows into the friction clutch mechanism, friction clutch operations are damaged. Therefore, conventionally, a concave slot for gathering the grease is formed on a cup washer which separates an upper worm wheel portion and a lower friction clutch portion in order to prevent the grease from flowing into the friction clutch portion. However, a demand for making the transmission device light and compact also makes the attachment space for the cup washer small and as a result, the amount of grease capable of being stored is decreased and it is feared that the grease will overflow from the cup washer. Therefore, it has been necessary to solve this problem.